Powered by SURF N SEA BACK PORCH BOOGIE#17 APRIL 28th
SNN BIG PICTURE: Monday 4/16/18
NPAC: The Jet Stream force is doing well for Spring for recent and continuation of storms spawning…the large upper flow (30,000+ feet up) has some 160kt pockets with some ‘troughs’ which helps to get the counter clockwise circulations at the surface. There’s been a quieting pattern relative to the past week which produced a few Winter Caliber events but we still keep small to moderate juices flowing through April 30th. There’s more and more High pressure domination however in the long range. We’ll need a regime change for anymore adv. level NW events in May.
Current: The NNW Sunday had some spots reach 7’ or 2.5X’s overhead at 14seconds on the declining powerful swell that reached easily 12’ with some isolated higher sets Saturday. Winds and weather were fickle/squally but all in all there were moments. This fades fast Monday to 2-4’ max. The Source came from a Hurricane level Low (up to 65kts + 35-45’ seas) tracking East crossing the dateline last Wednesday 4/11. Tho’ winds weakened Thursday the large storm was just 1200miles to the NNW. Thus, the 8-12++’ NNW with long periods. It’s not likely to see such a swell again till November.
Next: A weak distant Low far off Kamchatka over this weekend brings some small NW up to 3’ midday Wednesday-Thursday. More Spring like behavior.
Next: A better 40-50kt Low tracks east off the Kurils Monday 4/16 reaching the dateline Tuesday but staying up near the Central Aleutians with seas 20-30’. Most the swell goes NE of us. Though there’s enough fetch on it’s SW flank through it’s 4-day life to kick up some double overhead NW-NNW surf at 15sec by Friday. 18 sec Forerunners come Thursday the 19th with surf reaching just 2-4’ by evening. It’s going to fade pretty fast Saturday to 4’ max.
Next/Last: A weaker Eastward Low off Japan shows up Thursday the 19th with up to 40kt pockets. She crosses the dateline Friday 1200mi NW of us before pulling NE and weakening. WW3 says to expect some 3’ surf at 14 sec Monday the 23rd and after that don’t expect anything till Friday when another tiny NW comes in later Thursday the 26th.
Long Shot: There’s a small chance of a double overhead NW Friday the 27th from a broad gale Low coming down SE from off the West Aleutians Tuesday the 24th. The GFS (global forecast system) is outta wack as of Monday and won’t go out far enough to see if this ‘captured’ fetch stays aligned with Hawaii. Let you know next update.
SPAC: The Jet stream as of Monday 4/16 does not have high winds until far east from 120-90w. There’s a giant High off of New Z and the Jet flow in up and down and fairly broken.
The complex meridional (troughs N and South vs zonal) flows did enable a couple Lows to form at the surface a week ago. Thus, this week and further out we do have head high SSW events.
There’s another solid stream pointing NNE Friday-Saturday the 21st which starts over New Z and tracks off to the East which helps another broad Low pulse up some fun SSW angle right up the East coast. See below.
Recent/current: We have some fun overlapping swells building 16s SSW + South today and into Tuesday-Wednesday with a combo peak of 2-3’. Thursday will see more of a fade to occ head high or 3’ and down from there into the weekend.
The Sources: 1. a beautiful, compact Low spawns this weekend to the SE of New Z & moves right up the coast with a captured fetch. Seas ramped to 30-35’ as it intensified and widened Sunday the 8th. The storm occluded (stalled) into last Tuesday so this will be a longer than normal event here locally. There’s softer winds Wednesday but they’re still there. Source 2 was a Low under Tahiti during the same time tho’ the track and lifespan weren’t good.
Next Up: Lotsa energy in the Taz today Monday but it’s all drifting East. Still, with some luck we’ll get some 1’ swell at 16s popping Monday the 23rd and peaking Wednesday at head high; models hint of it lasting through Friday the 27th.
Last: On Sunday the 22nd there’s a decent Low tracking NE up the coast of New Z thanks to the meridional Jet mentioned at the start. Model suggest a 2’ deep water SSW at 15sec Sunday the 29th…which means solid 3’ sets or head high for most spots. It’s a long shot until we see the ‘actual’ storm this Sunday. Stay tuned.
Windward Shores: Recent/Current:
Cranking ENE trade swell at 3-5’ with advisories through Tuesday before leveling off a little Wednesday. This is due also not just to locally strong ENE trades but upstream winds which pushed the period from 8 to 9 seconds. Trades are around for the long haul so we don’t expect the windward side to drop below 3’ TFN.
Tropics: as of today there’s nothing for the next 7 days.
Your LATEST IN-DEPTH VIDEO PRESENTATION of HAWAII’S WAVES & WEATHER by SURF NEWS NETWORK
Terms: The split Jetstream is why all the Gulf and Alaskan storms are sending North swells. There’s that strong, persistent blocking ridge west of the dateline bumped the Jet up and over into the Bering Sea most November.
Notes: the spectral density graph in the SNN Buoy Page (link below) shows slivers of forerunners that initial text readings do not ‘show’ till later on written buoy updates. Also, note the vertical graph is not ‘wave height’ rather its a measure of wave energy in hertz (frequency or cylces/sec) for the whole ‘band’ (the distribution of power/period in the total wave energy field/spectrum). For SNN’s Buoys ‘per shore’ arrangement pls GO HERE
Links: Get the latest on the tropics at www.hurricanes.gov
For more on the Westpac Typhoons GO HERE
The Central Pacific Hurricane Center outlook for the 2017 Central Pacific Hurricane Season calls for 5 to 8 tropical cyclones to either develop or cross into the Central Pacific with a 40% chance for an above-normal season, a 40% chance for a normal season, and a 20% chance for a below-normal season. An average season has 4 to 5 tropical cyclones, which include tropical depressions, tropical storms, and hurricanes.
Tropical depression forms when a low-pressure area is accompanied by thunderstorms that produce a circular wind flow with maximum sustained winds below 39 mph. An upgrade to a tropical storm occurs when cyclonic circulation becomes more organized and maximum sustained winds gust between 39 mph and 73 mph. A tropical storm is then upgraded to Category 1 hurricane status as maximum sustained winds increase to between 74 mph and 95 mph. (The highest classification in the scale, Category 5, is reserved for storms with winds exceeding 156 mph).
Tropical cyclones go by many names around the world, and the terminology can get confusing. Once a tropical cyclone strengthens to the point where it has gale-force winds—39 mph or greater—it becomes a tropical storm. A storm that reaches tropical storm strength usually gets its own name to help us quickly identify it in forecasts and warnings. Once a tropical storm begins producing sustained winds of around 75 mph, we call the storm a typhoon in the western Pacific near Asia and a hurricane in the oceans on either side of North America. A “typhoon” and a “hurricane” are the same kind of storm, they just go by different names…it’s only a matter of geography.
NWS criteria for High Surf Advisories (first number) & Warnings (second number).
In coordination with civil defense agencies & water safety organizations in Hawai`i, the NWS uses the criteria below for the issuance of High Surf Advisories & Warnings in coordination with civil defense agencies & water safety organizations in Hawai`i.
All surf height observations & forecasts are for full ‘face’ surf height, or ‘trough to the crest’ of the wave.
Advisory and Warning Criteria Shoreline or Location
North-Facing Shores 15 Feet and 25 Feet
West-Facing Shores – Remaining Islands 12 Feet and 20 Feet
West-Facing Shores – Big Island 8 Feet and 12 Feet
South-Facing Shores 8 Feet and 15 Feet
East-Facing Shores 8 Feet and 15 Feet
‘Travel Time’ Buoy 51101 to Waimea Buoy. Distance: 269 nautical miles (~310 miles). Angle: 307 deg
Shoaling is the effect by which surface waves entering shallower water change in wave height (or grow) due to speed change (or slow down). Wavelength is reduced when going from deeper to shallower. The ‘energy flux’ must remain constant (nature’s liquid law) so the reduction in wave group (transport) speed is compensated by an increase in wave height (and thus wave energy density). Yeah, I know…waves are complex AND amazing.
Refraction is the change in direction of waves that occurs when waves travel from one medium to another or depth change. Refraction is always accompanied by a wavelength & speed change. Diffraction is the bending & spreading of waves around obstacles (‘reefs’ and openings).
High Surf Advisories & Warnings NWS criteria below in coordination with Hawai’i civil defense agencies & water safety organizations.
All surf height observations & forecasts are for the full face surf height, from the trough to the crest of the wave.
|North-Facing Shores||15 Feet||25 Feet|
|West-Facing Shores – Big Island||8 Feet||12 Feet|
|West-Facing Shores – Remaining Islands||12 Feet||20 Feet|
|South-Facing Shores||8 Feet||15 Feet|
|East-Facing Shores||8 Feet||15 Feet|
‘Travel Time’ Buoy 51101 to Waimea Buoy
Distance: 269 nautical miles (~310 miles)
Angle: 307 deg
Wave Wave Wave Depth Wave Direction (deg)———-
Period Length Speed Shallow 295, 305, 315, 325, 335, 345, 355
(s) (ft) (nm/h) (ft) Travel Time (hours)———-
10sec. 512. 15. 256. 17.3, 17.7, 17.6, 16.9, 15.7, 14.0, 11.9
12sec. 737. 18. 369. 14.5, 14.8, 14.6, 14.0, 13.0, 11.6, 9.9
14sec. 1003. 21. 502. 12.4, 12.7, 12.5, 12.0, 11.2, 10.0, 8.5
16sec. 1310. 24. 655. 10.8, ,1 1.1, 11.0, 10.5, 9.8, 8.7, 7.4
18sec. 1658. 27. 829. 9.6, 9.8, 9.8, 9.4, 8.7, 7.8, 6.6
20sec. 2047. 30. 1024. 8.7 8.9 8.8 8.4 7.8 7.0 5.9
22sec. 2477. 33. 1239. 7.9 8.1 8.0 7.7 7.1 6.3 5.4
24sec. 2948. 36. 1474. 7.2 7.4 7.3 7.0 6.5 5.8 4.9
Tropical Storm – winds 39-73 mph (34-63 kt)
Category 1 – winds 74-95 mph (64-82 kt)
Category 2 – winds 96-110 mph (83-95 kt)
Category 3 – winds 111-130 mph (96-113 kt)
Category 4 – winds 131-155 mph (114-135 kt)
Category 5 – winds 156 mph and up (135+ kt)
Please visit the Central Pacific Hurricane Center website at www.weather.gov/cphc for the most recent bulletins.
ENSO (The El Niño-Southern Oscillation) is a single naturally occurring climate phenomenon in three states or phases. These involve fluctuating ocean temperatures in the equatorial Pacific. … When temperatures in the ENSO region of the Pacific are near average it is known as ENSO ‘neutral’, meaning that the oscillation is neither in a warm or cool phase.The two opposite phases, “El Niño”(warmer than average) and “La Niña”(cooler than average) require certain changes in both the ocean and the atmosphere because ENSO is a coupled climate phenomenon. “Neutral” is in the middle of the continuum. The MJO (Madden-Julian Oscillation) is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverse the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average, unlike ENSO which is stationary. In a nutshell, a more active ENSO means more surf.